local network which mean a local folder map to a drive letter to keep thing consistent especially when it come to add/replace and upgrading storage.
On my main system I when back to 1.7.7 from 1.7.8 because of tracks being disable after some time or after being played. Not all track just certain ones.
On my main system I have the local folder mapped to a Drive letter.
If it's only certain tracks, are they all the same format as in maybe wma instead of mp3? If so, is there a codec missing from your encoders in 1.7.8 that's there in 1.7.7?